I apologize before-hand for this horrible webmail client and any mangling that it may do to the message.
I would *HIGHLY* recommend against trying to go around your Exchange admin's back to connect an unauthorized client to your mail environment. Depending on the behavior of the client it could cause server-side issues and cause a "resume producing event" for you (slang for getting you fired). We had an individual attempt something similar where I work and his client was misbehaving extremely badly, we suspect that the client that he was using was also infected with some sort of trojan. It caused the mailbox database that his mailbox was located in to produce *MASSIVE* quantities of log files (Exchange produces database transaction log files for every change to the mailbox database just like SQL server does for its databases). It would produce so many log files that it would cause the databases that used the same log file disk to go offline due to the log file disk running out of space. In our guy's case, he got lucky and senior management just slapped his hand. Your management might not be so understanding.
I, personally, wouldn't chance it without approval from your management and your Exchange admin.